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Two Interesting Inventions.

14th February 1907
Page 17
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Page 17, 14th February 1907 — Two Interesting Inventions.
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Which of the following most accurately describes the problem?

The Stanley, Automatic, Change-Speed Gear: the Broadhurst Spring Wheel.

Wu have, within the last fortnight, had • opportunities of examining two interesting inventions, both of which are applicable to utility vehicles. By the courtesy of Captain the Hon. F. %V. Stanley, one of our representatives was, last week, enabled to make an inspectioh and trial of his automatic, change-speed gear, and this should go far towards eliminating the difficulties of manual gear changing which are experienced upon motors generally. The device is situated, transversely, in front of the ordinary gear box, and consists, essentially, of two shafts, placed one in front of the other. The forward shaft carries two loose cams : the first of these is for changing speed upwards ; the second for decreasing speed ratios. Alongside each cam, and immovably attached to the shaft, are two pawls, which are, normally, kept clear of engagement notches in the cams by springs. The second shaft carries, for purposes which will be made apparent, two small fingers, or trips.

The object of the inventor is to supply a means whereby the different gear ratios are changed, when required, by the engine, so as to give the best efficiency without being dependent upon the driver, and, to do this, both the shafts are under the sole control of the motor. The first shalt of this device, which shaft carries the two loose cams, as mentioned above, is driven, directly, from the two-to-one valve camshaft, by gears and a longitudinal shaft, whilst the second operating shaft, to which are attached the trips, is controlled by a sensitive governor. This governor derives its motion from the periphery of the fly-wheel ; it is fitted with two springs, and, when the engine is run fling at normal r.p.m., which speed has been found by experiment, these springs are, practically, inoperative. Directly the engine speed increases, the two governor balls tend to fly outwards, which action pulls the " for ward " finger, or trip, upon the second shaft, into contact with the pawl upon the first shaft, and forces it into the notch in the adjacent cam. The cam, in this way, is locked upon its shaft, revolves, and actuates a bell crank, which pulls forward the fork in connection with the change-speed gear, and causes the next highest ratio to become engaged. Should the engine he able to rotate quickly enough, a higher ratio is, automatically, slipped in, and so on until the highest is reached, when the speed has to be governed by the throttle.

The reduction of the gear ratios is similar. Directly the engine speed begins to fall, the second spring on the governor tends to close the balls. and the second, or " backward," trip is brought into action, and locks the second cam, the first cam, of course, being inoperative. This action., by means of an identical cam to the first, in conjunction with its bell crank, forces the next lowest speed ratio into operation. The whole arrangement is ingenious and, comparatively, simple. Our illustrations are taken from an experimental apparatus, which is fitted to a Charron car. The gears, of which a face view appears in the adjoining illustration, will, in all probability, be eliminated in later types ; they are, only, for reducing the speed between the longitudinal shaft, which is driven from the two-to-one gear, and the cams. A worm drive will, in the future, be employed, to effect this reduction of speed.

In the Broadhurst spring wheel, an, apparently, successful attempt has been made to overcome some of the most prominent difficulties that militate against the general adoption of this

type of wheel. An incidental advantage claimed by the designer, is, that side-skidding is done away with to a large extent, owing to the feet that the tread of the wheel is, in reality, composed of three parallel, circular sec• times-, each of which is built up of an inner rim of channel steel, a wooden felly bedded into the channel, and an outer steel rim which runs upon the

road surface. The nominal tread is, therefore, divided into three tires of equal width, and each of these is capable of a restricted, relative movement, quite independently of its fellows. Anyone who has observed a heavy vehicle, when it was running upon a badly cambered road, must have been impressed with the extremely severe strains which are set up in the wheels, and hubs. The wheels bear, only, at one point on the surface of the tires, instead of adapting themselves to the inequalities of the road, with the result that the hub bushes wear out more quickly than would, otherwise, be the case. Now, in the Broadhurst wheel, it is claimed that the above-mentioned disadvantage is absent, owing to the fact that the three rims can conform, within limits, to the irregularities of the track upon which the wheel is travelling. It has, yet, to be shown that this construction falls within Article VI of the Heavy Motor Order.

Mark Mayhew, Limited, the wellknown milling company, of Battersea, has been giving this patent a trial, for about a fortnight, upon the front axle of a Leyland steam wagon, and, during this time, over soo miles have been covered by this single, steering wheel. The results have been satisfactory, and the vehicle has been running its allotted journeys the whole time. This record is promising, because the wheel is only in an experimental form, and its ultimate design will, most likely, be altered in sonic. details. Our second illustration has been prepared from a true-to-scale model, which was put at the disposal of this journal by Mr. Broadhurst, its inventor, after our representative's visit to Battersea last reek. The method of construction is, substantially, as follows :—Each of the three tread rings is furnished with four bearing pieces, and a series of laminated springs distribute the load upon them. These springs are bent, at their centres, in such a way that the two " arms " form an acute angle; in fact, the inventor calls them a " hairpin " type. Each arm of the springs is, for the steering wheel under notice, about eight inches in length, and the Leaves arc ti inch wide, and 5-16 inch thick. The springs are laid, radially, in each ring, and disposed in four pairs, each of which pairs is divided from its neighbour by one of the four bearing blocks, named above, which are immovably attached to the inner rim supporting the wooden felly, and furnished with steel rollers at the points of contact. One of the units will, now, be taken. A bolt is passed through the check plate, removed in the model illustration for the sake of clearness, through one side of the hub flange, through the eye of the spring, formed by bending it, through two other springs belonging to the other rims, with which we are not concerned at the monwnt, and, lastly, through the other hub flange. A second spring is held beside the first, in an identical manner, one of its "arms " coming against a second bearing block. It will, thus, be clear, that there are two " hairpin " springs between each pair of bearing blocks, but these springs are not under compression in any way. This requirement is brought about by the introduction of a cam bolt, placed between the contiguous " arms " of the two adjacent springs; this bolt passes through the cheek plate, near the periphery. When the wheel is assembled, and the second cheek plate put in place, the cam bolts are revolved a quarter turn, in order to force the spring " arms" apart, and to put a pressure of about eight cwt. upon each. In practice, the bearing blocks belonging to the inner and outer rims are opposite, whilst. those belonging to the central one are spaced, .angularly, between the former, or at 45 degrees to them. The maximum movement between the huh and treads is restricted to xi inch, which has been found to be ample for all ordinary conditions. It may be pointed out, that the cam bolts, which support the contiguous " arms " of any two adjacent springs, and the bolts passed through the eyes of these bent springs, are carried in the cheek plates, thus making them, relatively, immovable. The rims are, it will be noted, held in position by the inter-action of the springs, entirely, as exerted between the cam bolts and the bearing blocks. One peculiarity of the wheel, which is interesting, though not, at once, apparent, is the fact that, when a rim strikes an obstacle, it is pushed backwards, as well as upwards, and this compound action tends to eliminate shock.

The Broadhurst. wheel will be con, structed for use on motorbuses, and, in this case, each rim will be shod with a single, solid tire. The wheel is one of the best examples brought to our notice, but it is difficult, in the absence of actual experience, to estimate how it would behave when transmitting power. Arrangements are in hand, at the present time, for its manufacture on modified lines, by which it is expected that certain reductions in the weight will be effected, and a better distribution. of strength made. It may be mentioned that, in the case of the single front wheel which has been used by Mark Mayhew, Limited, the complete weight is close upon 3 cwt. ; also, with regard to the holes in the cheek plates, •which can be seen in the illustration to the left of this page, that •these are not slots, hut holes, intended for the bolts; they were at first drilled in the Wrong places. Whilst by no means free from all the fundamental difficulties which. charncterise the spring wheel, we must compliment Mr. Broadhurst upon his extreme ingenuity, and express the hope that, after suitable extended trial, success will crown his efforts.

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